Download Korsakoff Syndrome Topic Sheet

Korsakoff syndrome
A topic in the Alzheimer’s Association® series on understanding dementia.
About dementia
Dementia is a condition in which a person has significant difficulty with daily functioning
because of problems with thinking and memory. Dementia is not a single disease; it’s an
overall term — like heart disease — that covers a wide range of specific medical conditions,
including Alzheimer’s disease. Disorders grouped under the general term “dementia” are
caused by abnormal brain changes. These changes trigger a decline in thinking skills, also
known as cognitive abilities, severe enough to impair daily life and independent function.
They also affect behavior, feelings and relationships.
Brain changes that cause dementia may be temporary, but they are most often permanent and
worsen over time, leading to increasing disability and a shortened life span. Survival can vary
widely, depending on such factors as the cause of the dementia, age at diagnosis and
coexisting health conditions.
Korsakoff syndrome
Korsakoff syndrome is a chronic memory disorder caused by severe deficiency of thiamine
(vitamin B-1). Thiamine helps brain cells produce energy from sugar. When levels fall too
low, brain cells cannot generate enough energy to function properly.
Korsakoff syndrome is most commonly caused by alcohol misuse but can also be associated
with AIDS, cancers that have spread throughout the body, chronic infections, poor nutrition
and certain other conditions.
Korsakoff syndrome is often — but not always — preceded by an episode of Wernicke
encephalopathy, which is an acute brain reaction to severe lack of thiamine. Wernicke
encephalopathy is a medical emergency that causes life-threatening brain disruption,
profound confusion, staggering and stumbling, lack of coordination and abnormal involuntary
eye movements.
Because the chronic memory loss of Korsakoff syndrome often follows an episode of
Wernicke encephalopathy, the chronic disorder is sometimes known as Wernicke-Korsakoff
syndrome. But Korsakoff syndrome can also develop in individuals who have not had a clearcut prior episode of Wernicke encephalopathy.
Korsakoff syndrome and its associated thiamine deficiency is not the only mechanism
through which heavy drinking may contribute to chronic thinking changes and cognitive
decline. Alcohol misuse may also lead to brain damage through the direct toxic effects of
alcohol on brain cells; the biological stress of repeated intoxication and withdrawal; alcoholrelated cerebrovascular disease; and head injuries sustained when inebriated.
Prevalence
Scientists don’t know exactly how many people have Korsakoff syndrome. It’s widely
considered less common than Alzheimer’s disease, vascular dementia, frontotemporal
dementia or dementia with Lewy bodies. Like more common types of dementia, it may be
underdiagnosed.
Symptoms
Korsakoff syndrome causes problems learning new information, inability to remember recent
events and long-term memory gaps. Memory difficulties may be strikingly severe while other
thinking and social skills are relatively unaffected. For example, individuals may seem able to
carry on a coherent conversation but moments later be unable to recall that the conversation
took place or to whom they spoke.
Those with Korsakoff syndrome may “confabulate,” or make up, information they can’t
remember. They are not “lying” but may actually believe their invented explanations.
Scientists don’t yet understand the mechanism by which Korsakoff syndrome may cause
confabulation. The person may also see or hear things that are not there (hallucinations).
Diagnosis
Korsakoff syndrome is a clinical diagnosis representing a physician’s best judgment about the
cause of a person’s symptoms. There are no specific laboratory tests or neuroimaging
procedures to confirm that a person has this disorder. The syndrome may sometimes be hard
to identify because it may be masked by symptoms of other conditions common among those
who misuse alcohol, including intoxication or withdrawal, infection or head injury.
Experts recommend that a medical workup for memory loss or other cognitive changes
always include questions about an individual’s alcohol use.
Anyone admitted to the hospital for an alcohol-related condition should be professionally
screened for memory loss and cognitive change. The screening should include supplementary
questions to assess recent memory. If screening suggests impairment, the person should
receive a more detailed cognitive workup.
Causes and risk factors
Scientists don’t yet know exactly how Korsakoff syndrome damages the brain. Research has
shown that severe thiamine deficiency disrupts several biochemicals that play key roles in
carrying signals among brain cells and in storing and retrieving memories. These disruptions
destroy brain cells and cause widespread microscopic bleeding and scar tissue.
Researchers have identified several genetic variations that may increase susceptibility to
Korsakoff syndrome. Poor nutrition may also raise risk.
Most cases of Korsakoff syndrome result from alcohol misuse. Scientists don’t yet know why
heavy drinking causes severe thiamine deficiency in some alcoholics, while others may be
affected primarily by alcohol’s effects on the liver, stomach, heart, intestines or other body
systems.
Korsakoff syndrome may sometimes be associated with disorders other than alcohol misuse,
including anorexia, overly stringent dieting, fasting, starvation or weight-loss surgery;
uncontrolled vomiting; AIDS; kidney dialysis; chronic infection; or cancer that has spread
throughout the body.
Outcomes
Wernicke encephalopathy, a related disorder that sometimes precedes Korsakoff syndrome, is
a medical emergency. Untreated, it causes death in up to 20 percent of cases and progresses
to Korsakoff syndrome in 85 percent of survivors. Abnormal eye movements that occur in
Wernicke encephalopathy may respond to injectable thiamine within a few days. Lack of
coordination and clumsiness may begin to improve after about a week but may take several
months to clear up completely. Confusion also takes several months to clear up. As confusion
clears, the severe memory problems associated with Korsakoff syndrome may become more
noticeable.
In those who develop Korsakoff syndrome with or without a preceding episode of Wernicke
encephalopathy, there are few studies on long-term outcomes. Available data suggest that
about 25 percent of those who develop Korsakoff syndrome eventually recover, about half
improve but don’t recover completely, and about 25 percent remain unchanged. Some
research suggests that those who recover from an episode may have a normal life expectancy
if they abstain from alcohol.
Treatment
Some experts recommend that heavy drinkers and others at risk of thiamine deficiency take
oral supplements of thiamine and other vitamins under their doctor’s supervision.
Many experts also recommend that anyone with a history of heavy alcohol use who
experiences symptoms associated with Wernicke encephalopathy, including acute confusion,
prolonged nausea and vomiting, unusual fatigue or weakness, or low body temperature or
blood pressure, be given injectable thiamine until the clinical picture grows clearer.
Once acute symptoms improve, individuals should be carefully evaluated to determine if their
medical history, alcohol use and pattern of memory problems may be consistent with
Korsakoff syndrome. For those who develop Korsakoff syndrome, extended treatment with
oral thiamine, other vitamins and magnesium may increase chances of symptom
improvement. If there is no improvement, consideration should be given to treatment of
comorbid deficiencies and medical conditions, and the need for long-term residential care or
supportive accommodation.
Abstaining from alcohol is a cornerstone of effective long-term treatment. Those with
Korsakoff syndrome have a reduced tolerance for alcohol and may be at high risk for further
alcohol-related health problems.
TS-0092 | Updated May 2016